U.S. patent application number 11/251940 was filed with the patent office on 2006-05-04 for document illuminating apparatus, document reading apparatus and image forming apparatus permitting efficient cooling.
Invention is credited to Hideaki Matsui, Susumu Mikajiri.
Application Number | 20060092617 11/251940 |
Document ID | / |
Family ID | 36169096 |
Filed Date | 2006-05-04 |
United States Patent
Application |
20060092617 |
Kind Code |
A1 |
Mikajiri; Susumu ; et
al. |
May 4, 2006 |
Document illuminating apparatus, document reading apparatus and
image forming apparatus permitting efficient cooling
Abstract
A document illumination apparatus includes a first light source
configured to emit light. A first lower reflector is configured to
reflect the light emitted from the first light source. A first
upper reflector is configured to reflect the light reflected by the
first lower reflector to illuminate a document. A first
non-reflective area is disposed between the first lower and upper
reflectors.
Inventors: |
Mikajiri; Susumu; (Tokyo,
JP) ; Matsui; Hideaki; (Kanagawa, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Family ID: |
36169096 |
Appl. No.: |
11/251940 |
Filed: |
October 18, 2005 |
Current U.S.
Class: |
362/11 ; 355/70;
362/17; 362/297; 362/345; 362/346 |
Current CPC
Class: |
H04N 1/193 20130101;
H04N 1/03 20130101; G03G 2215/0417 20130101; H04N 1/0285 20130101;
H04N 1/0287 20130101; H04N 1/00981 20130101; G03G 15/04036
20130101; H04N 1/1013 20130101 |
Class at
Publication: |
362/011 ;
362/017; 362/345; 355/070; 362/297; 362/346 |
International
Class: |
G03B 15/02 20060101
G03B015/02; F21V 7/20 20060101 F21V007/20; G03B 27/54 20060101
G03B027/54 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 18, 2004 |
JP |
2004-303165 |
Oct 21, 2004 |
JP |
2004-307395 |
Apr 27, 2005 |
JP |
2005-130586 |
Aug 12, 2005 |
JP |
2005-235076 |
Claims
1. A document illumination apparatus, comprising: a first light
source configured to emit light; a first lower reflector configured
to reflect the light emitted from the first light source; a first
upper reflector configured to reflect the light reflected by the
first lower reflector to illuminate a document; and a first
non-reflective area disposed between the first lower and upper
reflectors.
2. The document illumination apparatus according to claim 1,
wherein the first non-reflective area comprises a first opening
configured to permit air flow therethrough.
3. The document illumination apparatus according to claim 2,
further comprising: a running unit configured to receive the first
light source and the first lower and upper reflectors mounted
thereon, the running unit configured to move horizontally.
4. The document illumination apparatus according to claim 3,
further comprising: a duct connected to the running unit, the duct
configured to permit air flow at least one of into and out of the
running unit.
5. The document illumination apparatus according to claim 1,
wherein the first lower and upper reflectors are integral with one
another.
6. The document illumination apparatus according to claim 3,
further comprising: a second light source configured to emit light;
a second lower reflector configured to reflect the light emitted
from the second light source; a second upper reflector configured
to reflect the light reflected by the second lower reflector to
illuminate the document; and a second non-reflective area disposed
between the second lower and upper reflectors.
7. The document illumination apparatus according to claim 6,
wherein the second non-reflective area comprises a second opening
configured to permit air flow therethrough.
8. The document illumination apparatus according to claim 7,
wherein the running unit is configured to receive the second light
source and the second lower and upper reflectors mounted
thereon.
9. The document illumination apparatus according to claim 7,
wherein the first and second openings are arranged at a
substantially same vertical elevation.
10. The document illumination apparatus according to claim 6,
wherein the first and second light sources and the first and second
reflectors are arranged symmetrically with respect to an optical
axis of the light reflected to illuminate the document.
11. The document illumination apparatus according to claim 6,
further comprising: first and second holders configured to hold the
first and second light sources, respectively; and first and second
retainers configured to retain the first lower and upper reflectors
and the second lower and upper reflectors, respectively.
12. The document illumination apparatus according to claim 11,
wherein the first holder and first retainer are integral with one
another.
13. A document illumination apparatus, comprising: a light source
configured to emit light; and a reflector configured to reflect
light emitted from the light source and to illuminate a document,
the reflector having a shape of an ellipse, wherein the ellipse is
inclined by an angle .theta. so that one focal point of the ellipse
is arranged on a center of the light source and another focal point
of the ellipse is arranged to illuminate the document, such that
the following formulas are satisfied; .theta. = .alpha. + .beta. +
.gamma. , and .times. .times. .alpha. .times. sin - 1 .function. (
R D ) , ##EQU7## where R is the radius of the light source, D is a
distance between the two focal points of the ellipse, the angle
.theta. is a lean angle of the ellipse to a plumb line to the
document, .alpha. is an angle between a major axis of the ellipse
and a nearest light ray to the light source, .beta. is a light
convergent angle, and .gamma. is an angle between a farthest light
ray from the light source and the plumb line to the document.
14. A document illumination apparatus, comprising: a light source
configured to emit light; and a reflector configured to reflect
light emitted from the light source to illuminate a document, the
reflector having a shape of an ellipse, wherein one focal point of
the ellipse is arranged on a center of the light source and another
focal point is arranged to illuminate the document, such that the
following formula is satisfied; Y .gtoreq. D 2 sin .times. .times.
2 .times. .theta. ##EQU8## where D is a distance between the two
focal points of the ellipse, .theta. is a lean angle of the ellipse
to a plumb line to the document and Y is a coordinate of an apex of
a right triangle which is bounded by a line between the two focal
points of the ellipse, the plumb line from the document and a
horizontal line extending from the another focal point.
15. The document illumination apparatus according to claim 13,
wherein the focal points are arranged such that the following
formula is satisfied; Y .gtoreq. D 2 sin .times. .times. 2 .times.
.theta. ##EQU9## where D is a distance between the two focal points
of the ellipse and Y is a coordinate of an apex of a right triangle
which is bounded by a line between the two focal points of the
ellipse, the plumb line from the document and a horizontal line
extending from the another focal point.
16. The document illumination apparatus according to claim 15,
further comprising: a mirror adjacent the reflector and configured
to reflect light from the document.
17. A document illumination apparatus, comprising: means for
emitting light; means for reflecting the emitted light; means for
reflecting the reflected light to illuminating a document; and a
non-reflective area disposed between the means for reflecting the
emitted light and the means for reflecting the reflected light.
18. The document illumination apparatus according to claim 17,
further comprising: means for introducing air, the means for
introducing air disposed in the non-reflective area.
19. A document reading apparatus comprising: the document
illumination apparatus according to claim 1.
20. An image forming apparatus comprising: the document
illumination apparatus according to claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a document illumination
apparatus, a document reading apparatus and an image forming
apparatus, and more particularly to one or more of these
apparatuses permitting efficient cooling of a lamp.
[0003] 2. Discussion of the Related Art
[0004] It is known to use an illumination apparatus in a document
reading apparatus of an image forming system, such as a copiers or
a scanner. The illumination apparatus uses a fluorescent lamp as a
light source to illuminate a document, so that the document can be
read by the reading apparatus.
[0005] The fluorescent lamp is commonly a xenon lamp which has a
high emission efficiency and relatively low power consumption. The
xenon lamp has a wider light emitting area and generates a greater
amount of light, although it has a lower brightness as compared to
a halogen lamp.
[0006] The amount of light emitted by the lamp is proportional to
an area of the glass tube coated with a fluorescent material. Thus,
a relatively large xenon lamp, such as a xenon lamp having a size
of 10 mm or more in diameter, is used to emit a large amount of
light.
[0007] The known illumination apparatus suffer from the
disadvantage that the large xenon lamp produces a relatively large
amount of heat. High temperatures within the illumination apparatus
adversely affect the longevity of the light source, and degrade
other components of the illumination apparatus.
[0008] Further, the adverse effects caused by these high
temperatures are compounded as illumination apparatuses are
continually reduced in size. In order to make the illumination
apparatuses more compact, it has been proposed to use more
reflectors to provide the light path. However, the use of more
reflectors increases the complexity of the illumination
apparatuses, and it is more difficult and expensive to provide an
accurate light path.
SUMMARY OF THE INVENTION
[0009] The present invention can provide a document illumination
apparatus including a first light source configured to emit light.
A first lower reflector is configured to reflect the light emitted
from the first light source. A first upper reflector is configured
to reflect the light reflected by the first lower reflector to
illuminate a document. A first non-reflective area is disposed
between the first lower and upper reflectors.
[0010] The present invention can provide a document illumination
apparatus including a light source configured to emit light, and a
reflector configured to reflect light emitted from the light source
and to illuminate a document, the reflector having a shape of an
ellipse. The ellipse is inclined by an angle .theta. so that one
focal point of the ellipse is arranged on a center of the light
source and another focal point of the ellipse is arranged to
illuminate the document, such that the following formulas are
satisfied; .theta. = .alpha. + .beta. + .gamma. , and .times.
.times. .alpha. .times. sin - 1 .function. ( R D ) , ##EQU1## where
R is the radius of the light source, D is a distance between the
two focal points of the ellipse, the angle .theta. is a lean angle
of the ellipse to a plumb line to the document, .alpha. is an angle
between a major axis of the ellipse and a nearest light ray to the
light source, .beta. is a light convergent angle, and .gamma. is an
angle between a farthest light ray from the light source and the
plumb line to the document.
[0011] The present invention can provide a document illumination
apparatus including a light source configured to emit light, and a
reflector configured to reflect light emitted from the light source
to illuminate a document, the reflector having a shape of an
ellipse. One focal point of the ellipse is arranged on a center of
the light source and another focal point is arranged to illuminate
the document, such that the following formula is satisfied; Y
.gtoreq. D 2 sin .times. .times. 2 .times. .theta. ##EQU2## where D
is a distance between the two focal points of the ellipse, .theta.
is a lean angle of the ellipse to a plumb line to the document and
Y is a coordinate of an apex of a right triangle which is bounded
by a line between the two focal points of the ellipse, the plumb
line from the document and a horizontal line extending from the
another focal point.
[0012] The present invention can provide a document illumination
apparatus including a subassembly for emitting. A sub-assembly is
used for reflecting the emitted light. A sub-assembly is used for
reflecting the reflected light to illuminating a document. A
non-reflective area is disposed between the sub-assemblies for
reflecting light.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] A more complete appreciation of the disclosure and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0014] FIG. 1A is a side view an image forming apparatus having a
document illumination apparatus according to the present
invention;
[0015] FIG. 1B is a detail view of a portion of the document
illumination apparatus of FIG. 1A;
[0016] FIG. 2 is a side view of a first running unit of the
document illumination apparatus;
[0017] FIG. 3 is a side view of another embodiment of a first
running unit;
[0018] FIG. 4 is a side view of another embodiment of a first
running unit;
[0019] FIG. 5A is an isometric view of the first running unit of
FIG. 2;
[0020] FIG. 5B is a detail view of a portion of the first running
unit of FIG. 2;
[0021] FIG. 6 is a side cross sectional view of another embodiment
of a document illumination apparatus;
[0022] FIG. 7 is side view of an ellipse of a reflector of FIG.
6;
[0023] FIG. 8 is a side cross section view of another embodiment of
a document illumination apparatus including two fluorescent
lamps;
[0024] FIG. 9 is a side schematic view showing estimated beam lines
of light of the document illumination apparatus of FIG. 6; and
[0025] FIG. 10 is a side schematic view showing estimated beam
lines of light of the document illumination apparatus of FIG.
8.
DETAILED DESCRIPTION OF THE INVENTION
[0026] In describing preferred embodiments of the invention shown
in the drawings, specific terminology is employed for the sake of
clarity. However, the disclosure of this patent specification is
not intended to be limited to the specific terminology so selected
and it is to be understood that each specific element includes all
technical equivalents that operate in a similar manner.
[0027] Referring now to the drawings, wherein like reference
numerals designate identical or corresponding parts throughout the
several views, a document illumination apparatus according to an
embodiment of the present invention is described.
[0028] FIG. 1A is a side view an image forming apparatus having a
document illumination apparatus, in accordance with the present
invention. The image forming apparatus includes a document reader
1, an image forming unit 2, a paper feed unit 3 and a writing unit
4. The document reader 1 includes a document illumination apparatus
10 and an automatic document feeder (ADF) unit 11. The image
forming unit 2 can include other units used in image forming, such
as a photo conductor 15, a charging unit, a developer unit, a
transfer unit, and the like.
[0029] The paper feed unit 3 feeds papers or other types of
recording sheets one after another to the image forming unit 2. A
document is fed to a document table 20 by the ADF unit 11, and is
read by the document illumination apparatus 10 arranged underneath
the document table 20. Image information which is read by the
document illumination apparatus 10 is detected and is converted to
an electrical signal. The electrical signal is processed in a
predetermined image forming manner. As a result, data for forming
an image is determined from the electrical signal. Based on the
data, a laser beam is directed to the photo conductor 15 from the
writing unit 4 to form an electrostatic latent image on the photo
conductor 15. In the image forming unit 2, the electrostatic latent
image formed on the photo conductor 15 is developed as a toner
image by applying toner from the developer unit. The toner image is
transferred and fixed on the paper fed from the paper feed unit
3.
[0030] FIG. 1B is a detail view of a portion of the document
illumination apparatus 10. The document illumination apparatus 10
includes the document table 20, a first running unit 21, a second
running unit 50 and a reading plate 60. The first and second
running unit 21 and 50 are configured to move in a predetermined
horizontal direction. The reading plate 60 includes a CCD
(charge-coupled device) to receive the image from the document.
[0031] The first running unit 21 includes a carriage 22, two lamps
30 and 40, reflection plates 31 and 41 and a mirror 25. The
carriage 22 moves on a guide rail (not shown). The lamps 30 and 40
can be fluorescent lamp such as a xenon or halogen lamp, and are
mounted on the carriage 22. The light emitted from the lamps is
reflected by the reflection plates 31 and 41 to illuminate a
surface of the document.
[0032] The second running unit 50 includes reflecting plates 52 on
a carriage 51. The reflecting plates 52 are configured to reflect
light rays reflected at the document in a predetermined direction.
The light rays are reflected from the mirror 25 and are reflected
by the reflecting plates 52 and then form an image of the document
on the CCD. The image formed on the CCD is subject to image
processing. The document illumination apparatus 10 converges the
light emitted from the lamps 30 and 40 with the reflection plates
31 and 41.
[0033] FIG. 2 is a side view of a first running unit of the
document illumination apparatus 10. The first running unit 21
includes a first light source unit LA, a second light source unit
LB and the mirror 25. The light source units LA and LB include the
lamps 30 and 40, lower reflectors 31a and 41a, and upper reflectors
31b and 41b, respectively. The lower and upper reflector 31a and
31b form the reflection plate 31 in the light source unit LA, and
the lower and upper reflector 41a and 41b form the reflection plate
41 in the light source unit LB.
[0034] The lower reflectors 31a and 41a reflect the light from the
lamps 30 and 40, respectively. The upper reflector 31b and 41b
reflect the light reflected from the lower reflectors 31a and 41a,
such that the light illuminates the document to be read OA. A
smooth reflection surface is formed on each of the reflectors, for
example, by a chemical polishing method, an electrolytic polishing
method, a surface treatment such as plating, or alumite treatment
through vapor deposition.
[0035] The lower and upper reflectors 31a and 31b are integral with
one another and can be formed as a single unit. Similarly, the
lower and upper reflector 41a and 41b are integral with one another
and can be formed as a single unit. By this arrangement, it is
possible to reduce the number of components, and ease and accuracy
of assembly are increased.
[0036] A non-reflective area is arranged between the lower
reflector 31a and the upper reflector 31b in the light source unit
LA. An opening 31c can be formed in the non-reflective area.
Similarly, in the light source units LB, a non-reflective area is
arranged between the lower reflector 41a and the upper reflector
41b. An opening 41c can be formed in the non-reflective area. Thus,
the non-reflective areas permit the lamps to be cooled by allowing
the introduction of cool air and the escape of heated air from the
openings 31c and 41c while the first running unit 21 moves in the
predetermined running direction. The opening 31c and 41c can be
arranged at a relatively same height to more easily permit air flow
through, and therefore more efficiently cool, the light source
units LA and LB.
[0037] In this embodiment, the light source units LA and LB are
arranged symmetrically with respect to an optical axis of the light
reflected to the document OA. The reflectors 31a, 31b, 41a and 41b
can be integral with one another, such that the reflectors are
formed in a single unit. By this arrangement, it is possible to
reduce the number of components, and ease and accuracy of assembly
are increased.
[0038] A light opening 35 is formed at a connection part between
the first and the second reflectors 31a and 41a so that the
reflected light rays pass to the mirror 25 located underneath the
running unit 21. The light opening 35 is sized to prevent excess
light from being incident on the mirror 25.
[0039] FIG. 3 is a side view of another embodiment of a first
running unit. The configuration of the first running unit 321 of
FIG. 3 is similar to the first running unit 21 shown in FIG. 2. In
the first running unit 321 a first light source unit LA is
separately arranged from a second light source unit LB. The first
and the second reflectors 331a and 331b are integral with one
another and formed as a single unit, and the first and the second
reflectors 341a and 341b are integral with one another and formed
as a single unit. This arrangement provides advantages similar to
those discussed above with respect to the arrangement shown in FIG.
2.
[0040] FIG. 4 is a side view of another embodiment of a first
running unit. The first running unit 421 includes an air duct 65
disposed outside of an opening 431c of a reflection plate 431, as
well as an air duct 66 disposed outside of an opening 441c of a
reflection plate 441. Each one of the air ducts 65 and 66 has an
extended tapered shape. When the first running unit 421 moves in
the lateral direction, cooling air flows into the first running
unit 421 via the duct 66 and heated air flows out of the first
running unit 421 via the duct 65.
[0041] As a result, it is possible to avoid problems caused by
overheating the first running unit. Although FIG. 4 shows the ducts
attached to the reflecting plates of the embodiment of FIG. 2, the
ducts can be used with other type of reflecting plates, for
example, the reflecting plates shown in FIG. 3.
[0042] FIG. 5A is an isometric view of the first running unit of
FIG. 2. FIG. 5B is a detail view of a portion of the first running
unit of FIG. 2. In this embodiment, the lamps 30 and 40 are
strip-type light sources having electrodes at both of their
respective ends.
[0043] As shown in FIG. 5B, a lamp-reflection plate holder 70,
which holds the electrodes, is mounted on a carriage 22. The lamp
40 is held on the carriage 22 and is arranged symmetrically with
respect to the lamp 30. Consequently, the lamps and the reflection
plate holders are symmetrically arranged on the carriage 22.
[0044] The lamp-reflection plate holder 70 is electrically
connected through electrodes arranged at both ends of the lamp 40.
The lamp-reflection plate holder 70 further includes a lamp holder
71 and a reflection plate keeper 75 arranged adjacent and beside
the lamp holder 71. The lamp holder 71 engages and mechanically
holds the electrodes. The lamp holder 71 and the reflection plate
keeper 75 can be formed as a single unit.
[0045] The lamp holder 71 includes a main body, terminals and lead
wires. The main body is formed from a heat-resisting resin
material. The terminals are arranged in the main body and the lead
wires extend from the terminals to connect to a power supply. The
lamp holder 71 also includes a fixed holder portion that fixes the
electrode at one side of the lamp and a removable holder portion
that is arranged at another side of the lamp, the holder portions
configured for mounting and dismounting of the electrodes.
[0046] The reflection plate keeper 75 is a holding device having a
removable (or fixable) configuration with both ends of a long side
of the reflection plates 31 and 41, and the reflection plate keeper
75 is integral with the lamp holder 71 (i.e., formed as a single
unit). The reflection plate keeper 75 includes a lower reflector
keeper 76 and an upper reflector keeper 77.
[0047] The lower reflector keeper 76 includes a slot or slit to
hold an end of the lower reflector 31a, and a slot or a slit to
hold an end of the lower reflector 41a. Thus, the lower reflectors
31a and 41a are held by the lower reflector keeper 76 at both ends.
Also, the upper reflector 31b and 41b are held by the upper
reflector keeper 77 at both ends. The lower and upper reflector
keepers 76 and 77 are integral with one another (i.e., formed as a
single unit), and are integral with the lamp holder 71. By this
arrangement, it is possible to reduce the number of components, and
ease and accuracy of assembly are increased.
[0048] In order to provide a compact document illumination
apparatus, it is important to optimize a positional configuration
and determine shapes of the components to efficiently illuminate
the document. In accordance with the following embodiments, a
suitable positional relationship among a lamp, a reflection plate
and a document table, as well as a shape of the reflection plate,
is disclosed.
[0049] FIG. 6 is a side cross sectional view of another embodiment
of a document illumination apparatus. The document illumination
apparatus 100 includes two fluorescent lamps 112 and 118 and
reflection plates. The reflection plate 111 is formed on a part
along a surface of an ellipse 110.
[0050] A major axis 117 of the ellipse 110 described by a formula X
2 A 2 + Y 2 B 2 = 1 ##EQU3## is tilted by an angle of .theta. to a
plumb line to a document, the plumb line extending from a mirror
114. A center of a lamp having radius R is arranged at one of focal
point of the ellipse 110. The focal point is a located at a far
side of the document. Another focal point is arranged located on
the document.
[0051] In this embodiment, .alpha., .beta. and .gamma. are defined
as follows: a is an angle between a major axis 117 of the ellipse
110 and a nearest light ray to the lamp 112; .beta. is a light
convergent angle; and .gamma. is an angle between a farthest light
ray from the lamp 112 and the plumb line to the document drawn from
the mirror 114. The angle .theta. satisfies the formula:
.theta.=.alpha.+.beta.+.gamma. and the angle .alpha. satisfies the
formula: .alpha. .times. sin - 1 .function. ( R D ) ##EQU4## where
D is a distance between two focal points and R is radius of the
lamp.
[0052] The fluorescent lamps 112 and 118 have lamp openings to
output light. As shown in FIG. 6, the lamp opening of the
fluorescent lamp 112 is arranged and oriented to face the opposite
side to the document toward a lower place and also to face the
plumb line extending to the document from the mirror 114. Thus,
this configuration contributes to reduce an amount of unnecessary
light for illuminating the document. Moreover, when the angle
.alpha. is determined in accordance with the formula, the light
reflected at the reflection plate is not limited by the lamp
itself, so that the light is efficiently used to illuminate the
document.
[0053] FIG. 7 is side view of an ellipse of a reflector of FIG. 6.
A right triangle which is bounded by a line between the two focal
points of the ellipse, the plumb line from the mirror 114 to the
document and a horizontal line extending from the focal point is
discussed. A coordinate Y of an apex of the right triangle is Y = D
* sin .times. .times. .theta. * cos .times. .times. .theta. = D 2
sin .times. .times. 2 .times. .theta. , ##EQU5## where D is a
distance between the two focal points and .theta. is the lean angle
of the ellipse to the plumb line to the document extending from the
mirror 114. The X axis is defined so as to be in a direction of the
major axis of the ellipse, and the Y axis is defined so as to be in
a direction of the minor axis of the ellipse.
[0054] If the ellipse of the reflection plate satisfies a formula
below passing through a point Y and the focal points are arranged
on the center of the fluorescent lamp 112 and the document surface,
an appropriate ellipse shape fitting in a relatively small space
can be determined. Y .gtoreq. D 2 sin .times. .times. 2 .times.
.theta. ##EQU6##
[0055] Namely, if the relation among three factors, such as
.alpha., .beta. and .gamma. and a value Y which restricts a size of
the ellipse satisfy the formulas, it is possible to determine an
appropriate positional relationship between the fluorescent lamp
112 and the reflection plate 111 and a shape of the reflection
plate 111. Based on this procedure, it is possible to efficiently
illuminate the document and reduce the incidence of flare.
[0056] A shaded area 115 shown in FIG. 6 shows a range of light
rays which is used to effectively illuminate the document. Because
the lamp opening of the fluorescent lamp 112 is facing the opposite
side to the document, light passing through the slit 116 and
shining directly on the mirror 114 can adversely affect the reading
performance of the document.
[0057] In this embodiment, the reflection plate 111 extends for a
sufficient length to a direction of the plumb line to the document
extending from a mirror 114 to avoid the direct incident light from
the lamp 112 on the mirror 114. Moreover, the size of the
reflection plate 111 is determined so as not to cover the slit 116.
Thus, the light emitted from a cylindrical-shaped light source is
converged by the reflection plate 111 and illuminates the document
on the document table, and then the light reflected from the
document shines through the slit 116.
[0058] FIG. 8 is a side cross section view of another embodiment of
a document illumination apparatus including two fluorescent lamps.
Specifically, the illumination apparatus 100 includes two
fluorescent lamps 123 and 125. In this embodiment, one focal point
of an ellipse shaped reflection plate 124 is located at the
document surface FA. However, another focal point is located at a
cross point FB of the lamp 123 on a line extending from a center of
the lamp to a middle of the lamp opening of the lamp with an angle
.phi., in contrast to the arrangement shown in FIG. 6.
[0059] FIG. 9 is a side schematic view showing estimated beam lines
of light of the document illumination apparatus of FIG. 6. In this
embodiment, one focal point is located at the center of the lamp
112 and another focal point is located at the document surface.
[0060] FIG. 10 is a side schematic view showing estimated beam
lines of light of the document illumination apparatus of FIG. 8. In
this embodiment, one focal point of an ellipse shaped reflection
plate is located at a cross point FB of the lamp 123 on a line
extending from the center of the lamp to the middle of the lamp
opening of the lamp with the angle .phi.. Similarly, a focal point
FC of another ellipse shaped reflection plate for lamp 125 is
arranged in a similar manner.
[0061] As shown in FIG. 9 and FIG. 10, light emitted from the lamps
123 and 125 is converged at the document surface. By this
arrangement, a more compact document illumination apparatus can be
provided with a smaller illumination system. Additionally, pairs of
lamps and reflection plates are arranged symmetrically with respect
to the optical axis of the light reflected to the document OA so
that a reading image area of the document is uniformly illuminated
with the light from both of the lamps. Therefore, it is possible to
avoid shading problems caused by curling of the document when the
document is relatively small.
[0062] Numerous additional modifications and variations are
possible in light of the above teachings. It is therefore to be
understood that within the scope of the appended claims, the
disclosure of this patent specification may be practiced otherwise
than as specifically described herein.
[0063] This patent specification is based on Japanese patent
applications, No. 2004-303165 filed on Oct. 18, 2004, No.
2004-307395 filed on Oct. 21, 2004, No. 2005-130586 filed on Apr.
27, 2005 and No. 2005-235076 filed on Aug. 12, 2005 in the Japan
Patent Office, the entire contents of which are incorporated by
reference herein.
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